The invention relates to a cutting insert used for chipforming and material removal operations, as well as a method for making the cutting insert. More specifically, the invention pertains to a cutting insert used for chipforming and material removal operations, as well as a method for making the cutting insert, wherein there is enhanced delivery of coolant adjacent the interface between the cutting insert and the workpiece (i.e., the insert-chip interface) to diminish excessive heat at the insert-chip interface.
In a chipforming and material removal operation (e.g., a milling operation), heat is generated at the insert-chip interface. It is well-known that excessive heat at the insert-chip interface can negatively impact upon (i.e., reduce or shorten) the useful tool life of the cutting insert. As can be appreciated, a shorter useful tool life increases overall operating costs and decreases overall production efficiency. Hence, there are readily apparent advantages connected with providing a cutting insert that facilitates a decrease of the heat at the insert-chip interface.
In this regard, U.S. Pat. No. 6,053,669 to Lagerberg discusses the importance of reducing the heat at the insert-chip interface. More specifically, Lagerberg mentions that when the cutting insert is made from cemented carbide reaches a certain temperature, its resistance to plastic deformation decreases. A decrease in plastic deformation resistance increases the risk for breakage of the cutting insert. U.S. Pat. No. 5,775,854 to Wertheim points out that a rise in the working temperature leads to a decrease in hardness of the cutting insert with a consequent increase in wear of the cutting insert. Each one of the Lagerbeg patent and the Wertheim patent discuss the importance of delivering coolant to the insert-chip interface.
Other patent documents disclose various ways to or systems for delivering coolant to the insert-chip interface. In this regard, the following United States Patent Applications, each of which is incorporated by reference herein, describe cutting insert that facilitate delivery of coolant to the insert-chip interface: U.S. patent application Ser. No. 11/654,833 (filed on Jan. 18, 2007) for a Milling Cutter and Milling Insert with Coolant Delivery by Prichard et al., U.S. patent application Ser. No. 11/654,877 (filed on Jan. 18, 2007) for a Milling Cutter and Milling Insert with Coolant Delivery by Prichard et al., and U.S. patent application Ser. No. 11/654,918 (filed on Jan. 18, 2007) for a Metalcutting System for Effective Coolant Delivery by Prichard et al.
Further, U.S. Pat. No. 6,045,300 to Antoun discloses using high pressure and high volume delivery of coolant to address heat at the insert-chip interface. U.S. Patent Application Publication No. 2003/00820118 to Kreamer discloses grooves between the cutting insert and a top plate. Coolants flows through the grooves to address the heat at the insert-chip interface. U.S. Pat. No. 5,901,623 to Hong discloses a coolant delivery system for applying liquid nitrogen to the insert-chip interface.
It is readily apparent that in a chipforming and material removal operation, higher operating temperatures at the insert-chip interface can have a detrimental impact on the useful tool life. These higher temperatures can cause premature breakage and/or excessive wear, which results in reduction or shortening of the useful tool life. It therefore would be highly desirable to provide a cutting insert used for chipforming and material removal operations wherein there is an improved delivery of coolant to the insert-chip interface.
In a cutting operation (e.g., turning operation or milling operation), the chip generated from the workpiece can sometimes stick (e.g., through welding) to the surface of the cutting insert (e.g., a turning insert or a milling insert). The build up of chip material on the cutting insert in this fashion is an undesirable occurrence that can negatively impact upon the performance of the cutting insert, and hence, the overall material removal operation. Thus, it would be highly desirable to provide a cutting inert (e.g., a turning insert or a milling insert), used for chipforming and material removal operations wherein there is enhanced delivery of coolant to the insert-chip interface so as to result in enhanced lubrication at the insert-chip interface. The consequence of enhanced lubrication at the insert-chip interface is a decrease in the tendency of the chip to stick to the cutting insert.
In a cutting operation such as, for example, a milling operation, there can occur instances in which the chips do not exit the region of the insert-chip interface when the chip sticks to the cutting insert. When a chip does not exit the region of the insert-chip interface, there is the potential that a chip can be re-cut. It is undesirable for the cutting insert to re-cut a chip already removed from the workpiece. A flow of coolant to the insert-chip interface will facilitate the evacuation of chips from the insert-chip interface thereby minimizing the potential that a chip will be re-cut. Hence, it would be highly desirable to provide a cutting inert (e.g., a turning insert or a milling insert), used for chipforming and material removal operations wherein there is enhanced delivery of coolant to the insert-chip interface so as to reduce the potential that a chip will be re-cut. The consequence of enhanced flow of coolant to the insert-chip interface is better evacuation of chips from the vicinity of the interface with a consequent reduction in the potential to re-cut a chip.
As is apparent from the above discussion, operational advantages are associated with using a cutting insert with a coolant delivery feature. However, the advantages extant with such a cutting insert that has a coolant delivery feature can diminish when the cutting insert has only one cutting edge. The operator must replace the cutting insert with only one cutting edge when the sole cutting edge wears past its useful life. It would thus be highly desirable to provide a cutting inert (e.g., a turning insert or milling insert) used for chipforming and material removal operations wherein there is enhanced delivery of coolant to the insert-chip interface and wherein the cutting insert presents a plurality of cutting edges. As one can appreciate, the presence of a plurality of cutting edges increases the value of the cutting insert to the customer in comparison to a cutting insert with only one cutting edge.
Powder metallurgical techniques typically can be useful to make a cutting insert used for chipforming and material removal operations. In this regard, a powder mixture is pressed into a partially dense green compact. Then, the green compact is subjected to a consolidation treatment (e.g., vacuum sintering, pressure sintering, HIPing and the like) to consolidate the green compact into a fully dense body. While these powder metallurgical techniques are satisfactory, the use thereof to make cutting tools of a more complex geometry may raise a manufacturing challenge. It would thus be highly desirable to provide a cutting inert (e.g., a turning insert or milling insert) used for chipforming and material removal operations wherein there is enhanced delivery of coolant to the insert-chip interface wherein the cutting insert is of a design, even though complex, that could be made via methods such as, for example, injection molding.